CA-229347: Pool_update.introduce doesn't need dom0 free disk 3 times of update size.
CA-229347: Pool_update.introduce doesn't need dom0 free disk 3 times of update size.

To install an update, we create a VDI and import the corresponding ISO file, which will be mounted.
Hence, dom0 no longer needs free disk space 3 times the size of the update.
This commit removes this check.

Signed-off-by: Hui Zhang <1290dea41121f0a9caa715ba0808e38da438ab06@citrix.com>

thomassa/xen-api,srowe/xen-api,euanh/xen-api,euanh/xen-api,thomassa/xen-api,euanh/xen-api,thomassa/xen-api,Frezzle/xen-api,euanh/xen-api,Frezzle/xen-api,thomassa/xen-api,Frezzle/xen-api,srowe/xen-api,srowe/xen-api,euanh/xen-api,srowe/xen-api,thomassa/xen-api,thomassa/xen-api,euanh/xen-api,srowe/xen-api,Frezzle/xen-api,Frezzle/xen-api